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Nuts And Bolts Explained - What Sizes?
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Nuts And Bolts Explained - What Sizes?
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Guide Nuts And Bolts Explained
- Thread starter Big Sandy
- Start date
educationalist
Big Landy Fan
Very good informative post and excellent advice; however to add to your guidance, it may help to mention that you could not apply this formula to measuring a countersunk bolt 'CSK', these you must measure the whole bolt length and not just under the head. (Though of course 'CSK' do not have a spanner size as they are usually bit driven).
Sandy M.
Big Landy Fan
And if it helps to clear up, or cloud the issue 
, with Imperial sizes the size of the bolt head [across the flats] is usually 1.5 times the diameter of the shank.
Metric bolts use the same principle but to keep spanner sizes sensible the figures for the bolt head are rounded down or up [ish!] to the nearest whole number.
, with Imperial sizes the size of the bolt head [across the flats] is usually 1.5 times the diameter of the shank.Metric bolts use the same principle but to keep spanner sizes sensible the figures for the bolt head are rounded down or up [ish!] to the nearest whole number.
A little note on grades and head markings.
You may have noticed that the heads of bolts and some nuts carry codes.
This is an industry standard and usually consists of the manufacturer (or importer) and the grade.
The most common grade (or property class)today is 8.8 or (Grade 8)
High tensile bolts would be of a heat-treated material to provide grade 10.9 or 12.9, and should be used where shear stresses are higher.
Finishes can be oil blacked (most cap head bolts use this), Bright zinc plate (better corrosion resistance) or a golden zinc plate with a chromate passivation-providing better corrosion protection of an often thinner zinc layer.
I have frequently reverted to my "Zeus book" for exact dimensions, and is well worth the money for one to identify the many different types found on our vehicles. Most are UNF (Unified fine), but previous owners may have used Metric and some BA threads are found in trim fittings, so identification is important.
You may have noticed that the heads of bolts and some nuts carry codes.
This is an industry standard and usually consists of the manufacturer (or importer) and the grade.
The most common grade (or property class)today is 8.8 or (Grade 8)
High tensile bolts would be of a heat-treated material to provide grade 10.9 or 12.9, and should be used where shear stresses are higher.
Finishes can be oil blacked (most cap head bolts use this), Bright zinc plate (better corrosion resistance) or a golden zinc plate with a chromate passivation-providing better corrosion protection of an often thinner zinc layer.
I have frequently reverted to my "Zeus book" for exact dimensions, and is well worth the money for one to identify the many different types found on our vehicles. Most are UNF (Unified fine), but previous owners may have used Metric and some BA threads are found in trim fittings, so identification is important.
Big Sandy updated Nuts And Bolts Explained with a new update entry:
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An update
Here's a handy sheet with different sizes and measurements, to help identify that random bolt..... By @Keeper_of_Tess
Bolt Identification
Dear All, I have dozens of little jars, tins, boxes, drawers and loose piles of assorted fasteners and I haven't a clue what they are. I have therefore trawled the internet to produce a spreadsheet to help with identification. I've sorted them by major diameter size. Where there are several...www.lrukforums.com
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